The invention is based on a container lid including an opening device. A lid of this kind, known by way of example from European Patent Application 000 4834, comprises a relatively thick carrier layer shaped from thermoplastic material in an injection molding process, the inside of which has combined with it a relatively thin aluminum/plastic laminate sheet, as a barrier layer. For the sake of easy opening of the lid, a weakening line is disposed surrounding a tear-open part; this weakening line penetrates the plastic layer completely in parts and is formed during the course of the injection molding process. A container lid of this kind is expensive because of the manner of its fabrication. First the carrier layer, as an outer part, is injection-molded in a mold, which is very slow and expensive. Then a sheet of aluminum/plastic laminate is sealed to the carrier layer. To the carrier layer and the laminate sheet must be delivered to the work station and positioned individually. The known lid also has the disadvantage that when the laminate sheet is applied to the angled sealing flange of the lid, wrinkles are formed, which can prevent a container from being tightly sealed by such a lid.
A container lid is also known from German Auslegeschrift DE-AS No. 20 23 923, having a tear-open part surrounded by indented lines, which is molded of a metal/plastic laminate. This lid has a relatively thick carrier and barrier layer comprising a metal plate, to the inside of which a relatively thin plastic film is glued and which acts as a corrosion and protective layer. The indented lines surrounding the tear-open part in this lid are impressed into the thick metal plate. Although the known lid is rigid and tight, it is very expensive because of the high proportion of metal it contains.
It is accordingly an object of the invention to create an easily openable container lid which is rigid, strong and tight and which can be formed in a simple manner from a strip of laminate.
The container lid according to the invention has the advantage that it can be formed in a non-wrinkling manner, in great quantity, by deep drawing a strip of plastic/metal laminate available in commerce, and its weakening line can be produced in a simple manner. Depending upon the configuration of the lid, the weakening lines can be impressed into the plastic carrier layer rapidly and in a positionally accurate manner with a heated indenting tool either before or after the forming.
As a result, advantageous further developments of the container lid disclosed are possible. A particularly advantageous feature is the disposition of ridges at either side of the weakening line. A thickening of the material in this manner provides good guidance as the tear-open part is being torn out, and it prevents the tear line from going off course. It is also possible to secure a pull tab directly to the outer carrier layer without great expense by heat-sealing means, the tab either comprising or being coated with a heat-sealable plastic.
The container lid according to the invention can be produced in great quantity and in a simple manner.